We got our first real glimpse at the Supergirl/Flash crossover yesterday in promotional photos and a tiny teaser, but this new teaser shows us the one moment of the episode we're all waiting for: a footrace between Supergirl and The Flash.

In the episode, called "Worlds Finest," Barry gets stuck in Supergirl's parallel universe and is enlisted to help her fight the supervillains Livewire and Banshee. But the most exciting part is seeing which hero is the "fastest person alive," and according to EP Andrew Kreisberg, "it's close." Our money is on The Flash, since he is the "fastest man alive" and all, but it would be funnier/better if Kara won, because then she could be the "fastest woman alive." (It would serve them right for using sexist language to begin with.) Plus, she is a demigod, while he's just a mere mortal, so it would actually make some measure of sense for her to beat him.

"Worlds Finest" – Kara gains a new ally when the lightning-fast superhero The Flash (Grant Gustin) suddenly appears from an alternate universe and helps Kara battle Siobhan, aka Silver Banshee, and Livewire in exchange for her help in finding a way to return him home, on SUPERGIRL, Monday, March 28 (8:00-9:00 PM) on the CBS Television Network. Grant Gustin crosses over as The Flash.